Process of making an adhesive and product thereof



Patented Oct. 16, 1934 UNITED STATES PROCESS OF MAKING AN ADHESIVE ANDPRODUCT THEREOF Irving Fink Laucks, Seattle, Wash, assignor to I. F.Laucks, Inc., Seattle, Wash, a corporation of Washington No Drawing.Application January 21, 1933, Serial No. 652,936

8 Claims.

Many advantages resulting from the use of cellulose xanthogenates asadhesives for wood and particularly in the manufacture of plywood havebeen disclosed in co-pending applications Serial Nos. 634,931, filedSeptember 26, 1932, and 646,525, filed December 9, 1932. There are,however, certain difficulties peculiarly connected with the use ofcellulose xanthogenates as plywood glues.

1 I have made a most important discovery of methods and processes ofmanufacture of viscoses and methods and processes of use thereof whichovercome these difiiculties which render viscoses available for economicand practical usefulness as adhesives for plywood.

To the accompluishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described, andparticularly pointed out in the claims, the following descriptionsetting forth in detail certain illustrative embodiments of theinvention, these being indicative however, of but a few of the variousways in which the principle 'of the invention may be employed.

For the purposes of this disclosure the term viscose may be defined toinclude all cellulose xanthogenates or salts of cellulose xanthogenicacid. The base material of such xanthogenates may be cotton, wood pulp,ground wood, wood flour, purified cellulose, oxycellulose, cellulosepar- 0 tially purified, revertedcellulose, seed coats as soya bean seedcoats, straw, etc. These xanthogenates are in general prepared bytreatment of the cellulosic material with caustic soda and with carbonbisulphide. It is particularly to be noted that the term viscose, asherein used, is not to be restricted to the one product of purecellulose originally described by Messrs. Cross & Bevan.

The use of glue by plywood plants is unique in several respects. Glue isused by this industry in 40 very large amounts. The glue demand is moreor less fluctuating even from hour to hour and the supply of glue mustbe immediately available to meet the fluctuating demands, furthermorethe final glue mixture must be easily made by relatively unskilledlabor.

The difiiculties of the use of viscose (cellulose xanthogenates) in themanufacture of plywood, particularly, are evident. The making-up of abatch of viscose from a cellulosic base requires time, varying with thenature of the base and the method used. The time may vary from hours toeven days in extreme cases. The plywood plant demand cannot be foreseenhours ahead and the use of a glue which takes so long to preparepresents many difficulties inplywood plant operation. It must beunderstood that these plants place a requirement of .not to exceedone-half hour forthe making up of the finished glue and in many casesthis time must be as short as fifteen minutes.

Furthermore, in general viscoses in the wet state have the inherentproperty of change. If a batch of wet viscose adhesive could be made upand held constant with only minor physical or chemical change until itwas used up over a period of hours or days, it would be possible tostore such prepared material ready to use. This, however, is not thecase. Physical and chemical changes do occur in viscose in the wet stateand these changes affect the usefulness and efliciency of the viscoseadhesives.

A substance having these characteristics is consequently very difficultoralmost impossible to introduce in the plywood industry, that is to theplants making plywood in large quantities and in which the making ofplywood is the chief or only business. Where plywood or veneers are madeon a smaller scale and where the necessity of large production is not sogreat, viscose, as it has been known so far, could be used with aconsiderable degree of efiiciency.

I have discovered, however, that I can produce viscose in a state whichis capable of being stored for indefinite periods without appreciabledeterioration and which can be readily converted into a 35 wet plywoodglue in a short time at point of use. This product then solves theproblem of the making of a plywood glue which will have the necessaryproperties of being readily and practically usable by the plywoodindustry and at the same time give the benefits that are inherent withreverted cellulose glue line.

To this end I precipitate a salt of cellulose xanthogenic acid. This maybe either the sodium or potassium salt, or it may be salt of one of theheavy metals, such as calcium, magnesium, zinc, etc. Some of these saltsare soluble in water and others are not. I find, however, that any ofthem may be dissolved in a caustic soda solution and that when used insolution with caustic soda they give better adhesion than when simply inwater solution.

To exemplify the process utilizing the sodium salt, I may make a viscosesolution as described in my co-pending applications Serial Nos. 634,931and 646,525. To the solution of viscose thus made I may add methyl orethyl alcohol until the sodium salt is precipitated. This precipitate iscollected, dried in suitable manner and ground through about 30-meshscreen. The requisiteamount of powder is then added to a 2% caustic sodasolution in a glue mixer and stirred for ten minutes, giving thefinished glue. This can be spread readily with the present spreaders inuse in the plywood industry and in fact can be handled just the same asthe protein glues the plywood industry is now accustomed to. Finergrinding of the dried product decreases the time required for stirringafter addition of same to the caustic soda solution. In place of alcoholto precipitate the sodium salt I may also use sodium chloride solutionfor example.

I may illustrate one method of utilization of myprocess as follows: 188parts of sulphite pulp are immersed in 4700 parts of 17% caustic sodasolution for three hours at approximately 65 F. The mass is then pressedto 752 parts of mercerized, crumbly cellulose and aged in this state for48 hours at a temperature of approximately 65 F. At the end of thisperiod 75 parts of carbon bisulphide are added and the mixture permittedto stand covered for approximately 2% hours. The yield resulting fromthis process is approximately 793 parts of cellulose xanthate in acrumbly pellet-like condition. This material is then dissolved in 1200parts of water and precipitated with 1600 parts of alcohol. Theprecipitate is removed and dried by any suitable means to approximately255 parts of material, which is the product in a stage suitable forstoring without appreciable change or deterioration of properties. Whenit is desired to make up the glue for use this 255 parts of precipitatedviscose is dissolved to approximately 2120 parts of a 2% solution ofcaustic soda resulting in a stringy glue having a viscosity ofapproximately 20 on the McMichael viscosimeter at a temperature of 60-65F.

Another illustration may be given as follows: Follow the same procedureas in the preceding example to the point of securing the 793 parts ofcellulose xanthate. This 793 parts of material is dissolved in 1200parts of water and precipitated with 750 parts of a 30% solution of zincchloride. This precipitate is separated and the moisture content removedto a total weight of 324 parts of material comprising the reactionproducts of the process. When it is desired to use this material for anadhesive it may be ground or otherwise comminuted, dissolved in 2430parts of 10% caustic soda solution resulting in a lightcolored stringyglue having a viscosity of approximately 10 on the McMichaelviscosimeter at a temperature of approximz. tely 65 F.'

The adhesives prepared in accordance with the examples above given areillustrative of the principles involved in my invention and are to beconsidered as illustrations only of such two methods.

There are many other methods of operation of the principles of theprocess and other raw materials may be used as bases and otherprecipitants may be used and other proportions of the variousingredients may be used.

To make the lime salt I precipitate a viscose solution with a solublecalcium compound, as for example calcium chloride, collecting and dryingthe precipitate, grinding same and making glue from it the same asdescribed with the sodium salt.

Another method of preparing the sodium salt may be exemplified asfollows; Prepare viscose up to the point of solution ofjsame, theninstead of water'being added to vthe reaction product of the carbonbisulphide and the mercerized cellulose, alcohol is added to thisreaction product. The addition of alcohol at this stage precipitates acompound which can be dried and stored with-- out appreciable change ordeterioration of its properties. This compound is believed to be thesodium salt of cellulose xanthogenic acid. This procedure hasadvantagesfrom a manufacturing standpoint, in that it uses less alcohol'and dilutes the alcohol less with water, thus making the recovery ofsame easier and more economical, and further one step in the manufactureof the dry compound is eliminated. Other precipitants may be substitutedfor alcohol in the last described method, as, for example, solutions ofcalcium chloride, zinc chloride, etc.

The dry cellulose xanthogenate compounds thus produced are stable aslong as they are kept dry and can be stored for a considerable length oftime, and as shown they also are readily converted into plywood glues.

Wherever the designation dry is applied to the product disclosed andclaimed herein it is to be understood that I include thereby not onlythe state designated as free from water or bone dry, but also the stateof the precipitate after being partially freed of water by pressing,filtering, centrifuging, etc. To come within my use of the designationdry the precipitate must be sufliciently freed from water so that it hasthe properties of a solid as distinguished from the properties of aliquid.

' I find that the life of the final wet glue made as above described maybe increased if instead of using caustic soda to dissolve the powder oneuses a solution containing sodium thiocarbonate, sodium sulphide, sodiumcarbonate as well as caustic soda. The substances named aredecomposition 110 products of the sodium salt of cellulose xantho--genic acid, that is they are formed when the sodium salt ofcellulose-xanthogenic acid decomposes and reverts to cellulose.

The adhesive product made in accordance with my invention is obviouslysuitable for gluing many substances other than wood.

Other modes of applying the principle of the invention may be employedinstead of those explained, change being made as regards the fea- 1,20tures herein disclosed, provided the features stated in any of thefollowing claims, or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. An adhesive comprising the reaction products resulting from thetreatment of a dry salt of cellulose xanthogenic acid with a solutionembodying the decomposition products of the sodium salt of cellulosexanthogenic acid and caustic soda.

2. An adhesive comprising the reaction products resulting from thetreatment of a dry salt of cellulose xanthogenic acid with a solutioncon taining sodium thiocarbonate and caustic soda.

3. An adhesive comprising the reaction products resulting from thetreatment of a dry salt of cellulose xanthogenic acid with a solutioncon- 1,977,445 prises preparing a dry salt of cellulose xantho,-.

8. A process of making an adhesive, which comprises preparing a drycalcium salt of cellulose xanthogenic acid, and redissolving such saltto glue-spreading consistency in an aqueous solution having an excess ofalkali over solution requirements.

IRVING FINK LAUCKS.

